Abnormalities in lipid kinetics may contribute to the increased prevalence of insulin resistance and hyperlipidemia in hypertensive compared with normotensive obese persons. Therefore, we evaluated glycerol rate of appearance (Ra) in plasma, an index of whole-body lipolytic activity, during basal conditions and 60 minutes of epinephrine infusion after 12 h and 84 h of fasting in 6 normotensive (BMI=39.9+I.8 kg/m2) and 6 hypertensive (BMI=38.7+I.6 kg/m2) obese persons. At 12 h of fasting basal fat oxidation rates were lower in the hypertensive than in the normotensive subjects (0.52+0.07 vs 0.84+0.07 mg-kg-1-min-1, respectively; P<0.01). Basal glycerol Ra and the integrated lipolytic response to epinephrine infusion was numerically, but not statistically significantly, lower in the hypertensive (1.58+0.21 umol.kg-1.min-1 and 69+35 umol.kg-1 60 min-1, respectively) than in the normotensive (2.27+0.26 umol.kg 1 min-1 and 89+18 umol.kg-1- 60 min~1, respectively) subjects. At 84 h of fasting, basal glycerol Ra and the integrated lipolytic response to epinephrine infusion were lower in the hypertensive (2.04+0.06 and 155+39 umol.kg-min1 and umol.kg-1. 60 min-1, respectively) than in the normotensive (2.50+0.13 and 313+35 umol.kg-1.min-1 and umol.kg-1. 60 min-1, respectively) than in the normotensive subjects (P<0.05). The data demonstrate that fat oxidation, basal whole-body lipolytic activity, and the lipolytic response to epinephrine are blunted in hypertensive compared with normotensive obese persons.